U.S. Pat. No. 4,475,565 issued Oct. 9, 1984 shows an earthquake valve including a weight in the form of a ball which is normally supported on the upper surface of a pedestal and which is displaceable laterally by shock forces to engage and deflect downwardly a tubular element disposed about the pedestal. Downward movement of the tubular element acts through a parallelogram mechanism to release a latch element and permit swinging movement of an arm carrying a valve, thus automatically closing the valve. The mechanism of this prior patent is very effective in reliably responding to shock forces, but is limited as to the size of valve which can be actuated by the device. The direct acting nature of the mechanism prevents it from exerting enough force to close a pipeline of the size required for many large scale users of gas, such as industrial plants or the like.